In recent years, with the rapid advance of the information industry, various information processing systems have been developed, and recording methods and units suitable for the information processing systems have been developed as well and put into practical use. Among the recording methods, an inkjet recording method, being capable of recording on many kinds of recording materials, relatively cheap and compact in the hard (system), and excellent in the quietness, is in wide use not only in offices but also in homes.
Furthermore, with the advance of higher resolving power of recent inkjet printers, so-called photograph-like high quality image recorded matters have become obtainable; that is, recording materials have been as well variously developed. From the viewpoint of possessing the commercial value as the recording material, excellent ink-absorbing property and image storability after recording, that is, non-bleaching property of an image during a long storage and non-deteriorating property of image quality due to bleeding are in demand.
As one of which ink absorption is improved, inkjet recording media in which an ink-receiving layer that has a three-dimensional structure that is made of inorganic pigment particles and a water soluble resin and has a high porosity is disposed are disclosed in Japanese Patent Application Laid-Open (JP-A) Nos. 10-203006, 10-217601, 11-20306. These are assumed capable of forming high definition images. However, in the inkjet recording media, during storage after printing, there is a problem in that the solvent diffuses together with a dye in the ink-receiving layer to cause the bleeding of an image (so-called “bleeding over time”). A recording medium having a porous layer formed by coating a mixture of porous silica particles and a pseudo-boehmite sol together with a binder is proposed as well in Japanese Patent Application Publication (JP-B) No.2650604. Surely, high ink absorption is exhibited and the color purity of printed matters can be improved. However, the bleeding over time cannot be successfully inhibited.
On the other hand, recording media where a silica porous layer is disposed as an underlayer and thereon a porous layer containing alumina or alumina hydrate is further laminated are described in JP-B Nos. 5-8393, 2605585. Owing to a configuration of the recording media, the ink absorption can be surely improved. However, the outermost layer containing alumina or alumina hydrate, being poor in the surface strength, is poor in the scratch resistance. Accordingly, there is a disadvantage in that a surface of the layer is likely to be damaged during handling.
As mentioned above, at present, an inkjet recording medium that can satisfy the bleeding over time of formed images and the scratch resistance thereof is not yet provided.